Combine multiple arrays containing observables into a unified array

I am facing the challenge of flattening a nested Observable into a single observable array. The Observable looks like this:

Observable<Observable<any[]>[]> values;

The inner arrays have the following structure:

[
  {id: 0, name: 'a'}, 
  {id: 1, name: 'b'}
], 
[
  {id: 0, name: 'a'}, 
  {id: 2, name: 'c'}
], 
[
  {id: 1, name: 'b'}, 
  {id: 3, name: 'd'}
]

We need to transform this into an Observable<any[]>, where the array should be combined as follows:

[
  {id: 0, name: 'a'},
  {id: 1, name: 'b'},
  {id: 2, name: 'c'},
  {id: 3, name: 'd'}
]

If anyone has any insight on how to accomplish this task, please share your expertise.

Answer №1

Give it a shot using the forkJoin method:

values.pipe(
    switchMap((values) => forkJoin(values)),
    map((result) => Array.from(new Set(arr.flat()))
).subscribe(result => {
    console.log(result)
})

This approach is effective in a specific scenario:

For this to work, each Observable within the array must trigger precisely once and resolve. If any of them triggers repeatedly or does not resolve, the forkJoin will not produce the desired outcome. In case the inner Observables are continuously triggered, utilizing combineLatest with mergeAll is more suitable. However, keep in mind that the output will consist of individual elements rather than a collective set.

Answer №2

Utilize the powerful Lodash JavaScript Library along with the versatile new Set(). Discover 3 distinct methods for flattening an array

flatten, flattenDeep, and flattenDepth

Answer №3

To tackle this issue in JavaScript, one option is to utilize the flat method or you could opt for a traditional loop approach with a reminder to take into account the compatibility of your chosen method.

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